Hitherto, as systems for carrying earth and sand by a dump truck in a wide field such as a quarry, unmanned dump truck operating systems have been well known. In these systems, for example, a travel course of an unmanned dump truck is taught in advance, and coordinate data for each predetermined distance of the travel course are stored in a storage device. During an unmanned traveling operation, the position, where the unmanned dump truck is actually traveling, is checked for each predetermined sampling time; and the deviation, between the actual travel position and the previously stored travel-course data is calculated. Then, operating control of the steering, the vehicle speed, the starting, and the stopping of the unmanned dump truck is performed so as to reduce the deviation; and the unmanned dump truck is controlled so as to travel along the previously stored travel course.
For example, Japanese Unexamined Patent Publication No. 5-297942 discloses an unmanned dump truck operating system having an unmanned dump truck, a loader, and a fixed station. The unmanned dump truck and the fixed station are provided with a bidirectional automatic tracking device; and a control circuit section, for automatically controlling the automatic tracking devices, is provided so that light waves emitted from the automatic tracking devices to each other are always received in the front thereof. This allows the distance between the fixed station, as a reference position, and the unmanned dump truck, and its direction, to be measured, so that the current position of the unmanned dump truck is calculated. In the operating system, a loading position where the loader loads earth and sand onto the unmanned dump truck, and an unloading position are provided; and an automatic travel course for the unmanned dump truck traveling between the loading position and the unloading position is obtained by teaching. The taught data of the travel course are stored in a storage device of the unmanned dump truck.
When the unmanned dump truck travels automatically, a travel control means of the unmanned dump truck is commanded to control the steering, the vehicle speed, the starting, and the stopping, so that the deviation between the current position of the traveling unmanned dump truck and the travel-course data in the storage device is reduced. In this way, the unmanned dump truck travels automatically between the loading position and the unloading position along the taught travel course.
In order to teach the travel course, the above publication proposes a method in which an operator of the dump truck gets into the driver's seat to operate the dump truck along a desired travel course, and travel position data on a predetermined sampling point at this time are stored in the storage device. In addition, another method is proposed in which the travel control, such as the steering, the forward-reverse switching, and the vehicle speed, is performed by an unmanned guiding device using a radio; the dump truck is operated by the unmanned guiding; and the travel position data on the sampling point are stored in the storage device similar to the above description.
Incidentally, in order to increase the operating efficiency at the time of the loading operation in the quarry, an operator of the loader frequently changes the loading position so that the loading position becomes as close as possible to the quarry. However, according to the above conventional unmanned dump truck operating system, the travel course to the loading position and the travel course from the loading position must be taught each time the loading position is changed. The operation for teaching the travel course is very troublesome, and the teaching work takes time, thus resulting in poor operating efficiency.
In addition, a method of traveling the dump truck to the loading position by unmanned guiding with the use of radio requires skill in the unmanned guiding operation. Therefore, problems arise in that it takes time for an unskilled operator to perform unmanned guiding, and that even the skilled operator tires easily due to the difficult unmanned guiding operation.